U.S. patent application number 10/298116 was filed with the patent office on 2004-05-20 for kink-resistant access sheath and method of making same.
This patent application is currently assigned to Applied Medical Resources Corporation. Invention is credited to Adlparvar, Payam, Aliahmad, Wassim R., Brustad, John R., Hart, Charles C., Hilal, Nabil, Pinedjian, Raffi S., Pravong, Boun, Tran, Canh T..
Application Number | 20040097881 10/298116 |
Document ID | / |
Family ID | 32297359 |
Filed Date | 2004-05-20 |
United States Patent
Application |
20040097881 |
Kind Code |
A1 |
Brustad, John R. ; et
al. |
May 20, 2004 |
Kink-resistant access sheath and method of making same
Abstract
A releasable mechanism such as a cap is adapted for use with an
access sheath having an elongate tube and a handle structure
disposed at a proximal end of the tube. The releasable mechanism is
sized and configured to fit the handle structure, which is shaped
like the bell of a horn, to further facilitate use with surgical
instrumentation. The releasable mechanism may operate as a separate
cap that snaps onto the handle structure to provide access pathways
to the sheath. The releasable mechanism may also be disposed at a
proximal end of a surgical instrument to be introduced into the
access sheath such that it may be interlocked with the sheath. In a
method of manufacturing a kink-resistant sheath, a wire is
initially coated with a plastic material, the coated wire is then
wrapped around a mandrel forming a plurality of windings, and the
wound coated wire is heated until the plastic material melts and
bonds the windings to form a wire-reinforced sheath. The plastic
material is preferably polyurethane but may be a thermoplastic, a
thermoset or any plastic material having hard and/or soft
durometer. The wound coated wire may be heated by capturing the
windings within a shrink tube or compressing the windings in a mold
and heating the windings until the sheath is formed. In another
aspect of the invention, a mandrel is used as part of an extrusion
process. In another aspect of the invention, another coating or
outside layer could be formed over the spring reinforcement by
dipping in a solvent based solution. In yet another embodiment of
the invention, a braid such as a polyester braid may be used
instead of or in addition to the coil spring to form a
kink-resistant sheath.
Inventors: |
Brustad, John R.; (Dana
Point, CA) ; Adlparvar, Payam; (Lake Forest, CA)
; Aliahmad, Wassim R.; (Irvine, CA) ; Tran, Canh
T.; (Garden Grove, CA) ; Hilal, Nabil; (Laguna
Niguel, CA) ; Pravong, Boun; (Corona, CA) ;
Pinedjian, Raffi S.; (Fountain Valley, CA) ; Hart,
Charles C.; (Summerville, SC) |
Correspondence
Address: |
Kenneth K. Vu
22872 Avenida Empresa
Rancho Santa Margarita
CA
92688
US
|
Assignee: |
Applied Medical Resources
Corporation
|
Family ID: |
32297359 |
Appl. No.: |
10/298116 |
Filed: |
November 15, 2002 |
Current U.S.
Class: |
604/164.07 ;
264/171.14; 427/2.1 |
Current CPC
Class: |
A61M 25/005 20130101;
A61M 25/0012 20130101; A61B 17/3415 20130101; A61B 2017/00526
20130101; B29C 48/0021 20190201; B29C 61/006 20130101; B29C 53/60
20130101; B29C 48/156 20190201; B29C 48/0011 20190201; B29L 2023/00
20130101; A61M 25/0662 20130101; B29C 48/154 20190201; A61M 25/0045
20130101; B29C 48/09 20190201 |
Class at
Publication: |
604/164.07 ;
264/171.14; 427/002.1 |
International
Class: |
A61M 005/178 |
Claims
1. An obturator adapted for insertion into an access sheath having
an elongate tube and a handle disposed at a proximal end of the
tube, the handle extending radially outwardly of the tube forming a
funnel with an opening leading into a lumen of the tube, the
obturator comprising: an elongate rod extending between a proximal
end and a distal end; and a releasable mechanism disposed at the
proximal end of the elongate rod which is removably attachable to
the handle of the sheath.
2. The obturator recited in claim 1, wherein the sheath is adapted
for insertion into a body cavity.
3. The obturator recited in claim 1, wherein when the releasable
mechanism is attached to the handle of the sheath, both the
obturator and the sheath can be passed as a single unit into a body
cavity.
4. The obturator recited in claim 1, wherein the attachment of the
obturator to the sheath precludes inadvertent advancement of the
sheath in front of the obturator.
5. The obturator recited in claim 1, wherein the releasable
mechanism is sized and configured to fit the opening of the funnel
of the handle.
6. The obturator recited in claim 1, wherein the releasable
mechanism is shaped like a cap.
7. The obturator recited in claim 1, wherein the handle of the
sheath is shaped like the bell of a horn.
8. A releasable mechanism adapted for use with an access sheath
having an elongate tube and a handle disposed at a proximal end of
the tube, the handle extending radially outwardly of the tube
forming a funnel with an opening leading into a lumen of the tube,
the releasable mechanism comprising: a cylinder having a lumen
extending between a proximal portion and a distal portion; and a
cap disposed at the distal portion of the cylinder which is sized
and configured to fit the opening of the funnel of the handle.
9. The releasable mechanism recited in claim 8, wherein the lumen
of the cylinder provides an access pathway to the sheath.
10. The releasable mechanism recited in claim 8, wherein the cap
operates to prevent passage of fluids or instrumentation into the
sheath.
11. The releasable mechanism recited in claim 8, wherein the sheath
is adapted for insertion into a body cavity.
12. The releasable mechanism recited in claim 8, wherein the cap is
configured to snap on the handle of the sheath.
13. The releasable mechanism recited in claim 8, further comprising
an opening extending from the cylinder to provide an additional
working channel into the sheath.
14. The releasable mechanism recited in claim 13, wherein the
opening is a sidearm.
15. The releasable mechanism recited in claim 13, wherein the
opening includes a Luerlock connector.
16. A method of manufacturing a kink-resistant sheath, comprising:
coating a wire with a plastic material; wrapping the coated wire
around a mandrel forming a plurality of windings; and heating the
wound coated wire until the plastic material melts and bonds the
windings forming a wire-reinforced sheath.
17. The method recited in claim 16, wherein the plastic material
comprises at least one of polyurethane, a thermoplastic material
and a thermoset material.
18. The method recited in claim 16, wherein the wire comprises at
least one of a metallic material and a second plastic material.
19. The method recited in claim 16, wherein the wire is coated with
the plastic material in a coextrusion process.
20. The method recited in claim 16, further comprising providing a
filament comprising a material different from the coating of the
wire.
21. The method recited in claim 20, wherein the coated wire is
alternatively wound with the filament around the mandrel.
22. The method recited in claim 16, further comprising capturing
the windings within a shrink tube and heating the shrink tube until
it encapsulates all of the windings.
23. The method recited in claim 16, further comprising compressing
the windings as the coated wire is being heated.
24. The method recited in claim 23, further comprising providing a
mold to compress the windings.
25. The method recited in claim 22, further comprising removing the
shrink tube after the sheath is cooled.
26. The method recited in claim 16, further comprising removing the
wire-reinforced sheath from the mandrel after the sheath is
cooled.
27. The method recited in claim 16, wherein the wound coated wire
is heated until the plastic material is formed above, below and
between all the windings.
28. The method recited in claim 16, further comprising dipping the
sheath in a solvent based solution forming an outer layer of the
sheath.
29. A method of manufacturing a kink-resistant sheath, comprising:
coating a mandrel with a first layer of plastic material to form an
inner tube; placing a spring reinforcement over the inner tube; and
coating the spring reinforcement with a second layer of plastic
material to form an outer tube of a spring-reinforced sheath.
30. The method recited in claim 29, wherein the inner tube is
formed in an extrusion process.
31. The method recited in claim 29, wherein the inner tube is
formed in a molding process.
32. The method recited in claim 29, wherein the outer tube is
formed in an extrusion process.
33. The method recited in claim 29, wherein the outer tube is
formed in a molding process.
34. The method recited in claim 29, wherein the spring
reinforcement is a pre-wound wire comprising at least one of a
metallic material and a second plastic material.
35. The method recited in claim 29, wherein the spring
reinforcement is a wire comprising at least one of a metallic
material and a second plastic material wound around the inner
tube.
36. The method recited in claim 29, further comprising dipping the
sheath in a solvent based solution forming an outer layer of the
sheath.
37. A method of manufacturing a kink-resistant sheath, comprising:
coating a mandrel with a first layer of plastic material to form an
inner tube; placing a spring reinforcement over the inner tube; and
dipping the spring-reinforced inner tube in a solvent based
solution to form an outer layer of the sheath.
38. The method recited in claim 37, wherein the outer layer is
impervious.
39. A method of manufacturing a kink-resistant sheath, comprising:
coating a mandrel with a first layer of plastic material to form an
inner tube; placing a braid over the inner tube; and coating the
braid with a second layer of plastic material to form an outer tube
of a braid-reinforced sheath.
40. The method recited in claim 39, wherein placing the braid over
the inner tube comprises molding the braid to the inner tube.
41. The method recited in claim 39, wherein placing the braid over
the inner tube comprises fusing the braid to the inner tube.
42. The method recited in claim 39, wherein placing the braid over
the inner tube comprises bonding the braid to the inner tube.
43. The method recited in claim 39, further comprising placing a
spring reinforcement over the braid.
44. The method recited in claim 43, wherein the spring
reinforcement has a length x and the braid has a length of
approximately 2x.
45. The method recited in claim 44, further comprising inverting
the access braid over the spring reinforcement.
46. The method recited in claim 39, wherein the braid is made of
polyester.
47. The method recited in claim 39, further comprising heat fusing
the braid to prevent axial stretching of the braid.
48. The method recited in claim 39, wherein the braid comprises a
plurality of woven fibers made of plastic.
49. The method recited in claim 39, wherein the braid comprises a
plurality of woven fibers made of metal.
50. The method recited in claim 39, wherein the braid comprises a
plurality of woven fibers made of a combination of plastic and
metal.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] This invention generally relates to medical devices and,
more specifically, to kink-resistant surgical access devices
adapted to introduce surgical instrumentation into body conduits
and methods of making same.
[0003] 2. Discussion of Related Art
[0004] Surgical access devices such as sheaths and catheters have
long been used to access body conduits. Surgical access devices
typically include an access sheath and an obturator or dilator
inserted therethrough to facilitate introduction of the access
sheath into a body conduit. Once the sheath is positioned inside
the body conduit, the obturator is removed leaving a working
channel for fluid delivery, fluid recovery, implant delivery and,
on many occasions, they provide an access pathway for an instrument
such as an endoscope. It follows that such a sheath needs to be as
durable and flexible as possible. A serious problem arises when an
access sheath is bent or twisted causing the sheath to kink. A
kinked sheath is useless because it cannot communicate and because
it will not allow the passage of an instrument such as a guidewire
or an endoscope. In addition, a kinked sheath may allow an
endoscope or other device to puncture the wall. This could present
a danger to the body conduit into which the sheath has been
inserted. Consequently, the kinked sheath must be removed and/or
replaced. As such, there has been a need in the art for an access
sheath having a kink-resistant construction. U.S. Pat. No.
5,380,304 (the '304 patent) and U.S. Pat. No. 5,700,253 (the '253
patent) attempt to address the kinking problem by disclosing a
sheath comprising an inner tube, a flat wire coil compression
fitted around the inner tube, and an outer tube connected to the
inner tube through the spacings between the wire coil.
Specifically, the outer surface of the inner tube is chemically
etched to form a rough outer surface to which the outer tube is
mechanically connected using a heat shrinking and formation
process. There is still a need, however, for alternative and
improved methods of manufacturing kink-resistant sheaths for use in
body conduits that are effective, cost-efficient and provide good
yields.
[0005] Furthermore, the present access sheath has been provided in
the form of an elongate tube that has tended to migrate distally
and, in some cases, have disappeared beneath the body conduit such
as the urethral meatus. U.S. patent application Ser. No. 09/882,630
(Publication No. 2002/0038115 A1), which is hereby incorporated by
reference, addresses this problem by providing an access sheath
having an enlargement at the proximal end to prevent migration and
to facilitate the insertion and removal of instrumentation. In
particular, the sheath includes a handle structure at the proximal
end that is sized and shaped to accommodate engagement by a user's
hand disposed in its natural position with the palm facing the
user. Specifically, the handle has a funnel structure that
facilitates the introduction of instrumentation into the working
channel of the sheath. As a result, the sheath is positioned in a
relatively stationary orientation during the insertion and removal
of instrumentation. However, these sheaths with handle structures
at the proximal ends have large openings and, therefore, it would
be desirable to provide a mechanism such as a cap that releasably
attaches to the handle structure to further facilitate use with the
surgical instruments.
SUMMARY OF THE INVENTION
[0006] The present invention is directed to a releasable mechanism
such as a cap adapted for use with an access sheath having an
elongate tube and a handle structure disposed at a proximal end of
the tube, the handle structure extending radially outwardly of the
tube forming a funnel with an opening leading into a lumen of the
tube. The releasable mechanism is sized and configured to fit the
opening of the funnel of the handle structure, which is shaped like
the bell of a horn, to further facilitate use with surgical
instrumentation. The releasable mechanism may operate as a separate
cap that snaps onto the handle structure to provide access pathways
to the sheath or prevent passage of fluids or instrumentation into
the sheath. The releasable mechanism may also be disposed at a
proximal end of a surgical instrument to be introduced into the
access sheath such that it may be interlocked with the sheath. The
releasable mechanism may include additional openings that provide
additional working channels into the sheath.
[0007] In a first method of manufacturing a kink-resistant sheath
of the invention, a wire is initially coated with a plastic
material, the coated wire is then wrapped around a mandrel forming
a plurality of windings, and the wound coated wire is heated until
the plastic material melts and bonds the windings to form a
wire-reinforced sheath. The plastic material is preferably
polyurethane but may be a thermoplastic, thermoset or any plastic
material having hard and/or soft durometer. The wound coated wire
may be heated by capturing the windings within a shrink tube or
compressing the windings in a mold and heating the windings until
the sheath is formed. In another method of the invention, a wire is
alternatively wound around a mandrel in a multifilar fashion with a
filament comprising a material different from the plastic coating
of the wire. In yet another embodiment of the invention, a hard
plastic/soft plastic multifilar is wound around a mandrel in place
of the coated wire.
[0008] In another aspect of the invention, a mandrel is used as
part of an extrusion process. In this process of manufacturing a
kink-resistant sheath, the mandrel is coated with a first layer of
plastic material to form an inner tube, a spring reinforcement is
then placed over the inner tube, which is then coated with a second
layer of plastic material to form an outer tube of the sheath. The
inner tube and outer tube may be formed by either extrusion or
molding. The spring reinforcement may be a pre-wound wire or a wire
wound around the inner tube. The material of the wire, the hardness
of the wire, the pitch of the windings and the shape of the wire
could vary depending on the application of the sheath. The wire,
e.g., may comprise a metallic and/or plastic material. In addition,
the wire may be round, rectangular, hexagonal or any other shape
that facilitates interlocking of the windings.
[0009] In another aspect of the invention, another coating or
outside layer could be placed over the spring reinforcement in a
dipping process. In particular, after the mandrel has been coated
and the spring reinforcement has been placed or wrapped, the spring
reinforcement is then dipped in a solvent based solution to form
the outer layer of the sheath. This final coating could be formed
on the sheath using a dipping process either in place of or in
addition to the outer layer formed by extrusion. That is, the final
coating could be extruded and/or dipped. In yet another embodiment
of the invention, a braid such as a polyester braid may be used
instead of or in addition to the coil spring to form a
kink-resistant sheath. The braid may comprise of woven fibers made
of plastic, metal or any combination of plastics and metals. The
braid may be heat fused to prevent axial stretching. Furthermore,
the braid may be insert molded, fused or bonded onto the
sheath.
[0010] These and other features and advantages of the invention
will become more apparent with a description of preferred
embodiments and reference to the associated drawings.
DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1 is a perspective view illustrating a sheath having a
handle with an obturator having a releasable mechanism adapted for
use with the handle of the sheath;
[0012] FIG. 2 is a perspective view illustrating the obturator
operatively disposed within the sheath;
[0013] FIG. 3 is a side view illustrating the obturator with a cap
operatively disposed within the sheath with the handle;
[0014] FIG. 4 illustrates another embodiment of a releasable
mechanism having multiple openings;
[0015] FIG. 5 illustrates a coated wire being wrapped around a
mandrel forming a reinforcement spring in a process of
manufacturing a kink-resistant sheath in accordance with an
embodiment of the invention;
[0016] FIG. 6 illustrates the heating process of the wound coated
wire using a shrink tube in a process of manufacturing a
kink-resistant sheath of the invention;
[0017] FIG. 7 illustrates the removal of the shrink tube after
heating of the wound coated wire in a process of manufacturing a
kink-resistant sheath of the invention;
[0018] FIG. 8 illustrates a coating of the spring reinforcement in
a dipping process in accordance with another embodiment of the
invention;
[0019] FIG. 9 illustrates a coated wire being alternatively wound
around a mandrel with a filament comprising a material different
from the coating of the wire;
[0020] FIG. 10 illustrates a mandrel being used in an extrusion
process in accordance with another embodiment of the invention;
[0021] FIG. 11 illustrates a side view of a braid and a tube prior
to being fused in accordance with another embodiment of the
kink-resistant sheath of the invention;
[0022] FIG. 12 illustrates fusing of the proximal portion of the
braid and the distal portion of the tube;
[0023] FIG. 13 illustrates a side view of a braid and a tube
extruded with a plastic material prior to being fused;
[0024] FIG. 14 illustrates fusing of the braid and the tube;
and
[0025] FIG. 15 illustrates a coating of the fused braid and tube
with a solvent based solution.
DESCRIPTION OF PREFERRED EMBODIMENTS AND BEST MODE OF THE
INVENTION
[0026] An access sheath is illustrated in FIG. 1 and is designated
generally by reference numeral 10. In FIG. 1, the sheath 10 is
illustrated in combination with a separate, but associated, dilator
or obturator 12. The sheath 10 has the general configuration of an
elongate tube 14 having an axis 16 which extends between a proximal
end 18 and a distal end 21. A handle 23 is disposed at the proximal
end 18 of the tube 14 and provides access into a working channel 25
of the tube 14. The handle 23 is formed as a radial enlargement
having a distally-facing surface and a proximally-facing surface.
The distally-facing surface has a generally concave configuration
which provides a gradual enlargement inhibiting migration of the
sheath 10 into a body cavity such as the ureter. The concave
configuration is sized to receive adjacent fingers of a user's hand
disposed in its natural position, in order to facilitate the
stationary orientation of the sheath 10. The proximal-facing
surface has a generally convex configuration providing for an
increased funneling of an instrument as it is inserted into the
working channel 25 of sheath 10. Thus, the handle 23 has the
general configuration of the bell of a horn. This configuration is
not only ergonomically comfortable, but also highly practical in
addressing the problems of migration, as well as instrument
insertion and removal.
[0027] The obturator 12 will typically have the configuration of an
elongate rod 30 extending between a proximal end 32 and a distal
end 34. In a preferred embodiment of the invention, a releasable
mechanism 36 shaped like a cap is disposed at the proximal end 32
and a tapered tip 38 is formed at the distal end 34. The obturator
12 is adapted to be inserted into the working channel 25 of sheath
10 with the releasable mechanism 36 extending proximally of the
sheath 10, and the distal end 34 extending distally of the sheath
10. This operative position of the obturator 12 within the sheath
10 is illustrated in the assembled view of FIG. 2. A side view of
the assembled combination is illustrated in FIG. 3. The releasable
mechanism 36 is provided to removably attach the obturator 12 to
the handle 23 of sheath 10.
[0028] When locked in place with the releasable mechanism 36, the
obturator 12 and sheath 10 can then be passed as a single unit over
an instrument such as a guidewire. This arrangement precludes
inadvertent advancement of the sheath 10 in front of the obturator
12, which could greatly impede proper passage of the sheath through
a body cavity such as the ureter. The releasable mechanism 36 is
sized and shaped to fit the handle 23. Once the obturator/sheath
combination has been advanced to the desired position in the body
cavity, the obturator 12 can be removed from the sheath 10 by
removing the releasable mechanism 36. Another surgical instrument
having a releasable mechanism disposed at its proximal end may then
be introduced into the sheath 10, or a separate releasable
mechanism may be attached to the handle 23 to prevent passage of
fluids or instrumentation. It is appreciated that the releasable
mechanism 36 may have different configurations including a snap-on
cap as illustrated in FIGS. 1-4, a twist-on cap and any foreseeable
releasable mechanism that fits the handle 23 of sheath 10. It is
further appreciated that the releasable mechanism may include
additional openings such as Luerlock connectors or sidearms
providing additional working channels into the sheath as
illustrated in FIG. 4.
[0029] Another aspect of the invention is the tube 14 may be formed
with a spring coil to provide a high degree of kink resistance. As
discussed above, there are many advantages to a kink-resistant
design of the access sheath such as safety and easy passage of
instrumentation. The '304 and '253 patents disclose one such design
by reinforcing the elongate tube of the access sheath with a coil.
The current methods of fabricating kink-resistant access sheaths,
however, are time-consuming, costly and do not provide good yields.
Moreover, the fabricated access sheaths do not have a good shelf
life. This is because the current manufacturing processes include
several challenges. In one example, a current manufacturing process
undergoes a dipping process where (1) a mandrel is first dipped in
a plastic or PVC material, (2) a wire is then wrapped or wound
around the dipped mandrel, and (3) the assembly is then dipped
again in the plastic or PVC material multiple times to form the
access sheath. While this is a feasible method of producing a
kink-resistant access sheath, it is time consuming, costly and
produces undesirable yields. The present invention, accordingly,
provides alternative methods of manufacturing kink-resistant access
sheaths that are more efficient, less costly and provide better
yields and improved shelf life.
[0030] In a first method of the invention as illustrated in FIG. 5,
a wire 50 is initially coated with a plastic material 52, e.g., in
a coextrusion process; the coated wire 50 is then wrapped or wound
on a straight or tapered mandrel 54 forming a desired reinforcement
spring 56 (i.e., forming a profile of the resultant tube); after
wrapping, the wound coated wire is heated until the plastic
material 52 melts and bonds the windings to form the resultant tube
or sheath; and once cooled, the sheath is removed from the mandrel
54. It should be noted that the wound coated wire is heated until
the plastic material 52 is formed above, below and in between the
wire 50. The wire/plastic coextrusion may be round, have straight
edges that can be laid adjacent to each other when winding or have
interlocking shapes. The wound coated wire may be heated in one of
several ways including: (i) capturing the windings within a shrink
tube 60 as illustrated in FIG. 6 and heating until the shrink tube
60 encapsulates all the windings and the sheath is formed; and (ii)
using a mold to compress the windings and heating the windings
until the sheath is formed. The heat shrink tube or mold is then
cut or removed from the sheath as illustrated in FIG. 7. That is,
after the plastic material such as polyurethane has melted together
to form the sheath with spring reinforcement, the shrink tube is
cut away and the mandrel is removed.
[0031] It is appreciated that the plastic material could be
polyurethane, a thermoplastic, a thermoset or any plastic material
having hard and/or soft durometer. It is further appreciated that
the coated wire could be wound onto the mandrel in a multifilar
fashion with materials having alternating durometers as illustrated
in FIG. 9. In this embodiment, a wire 90 coated with a more rigid
material 92 is alternatively wound with a filament 94 comprising a
softer material. The wound coated wire would perform like a spring
coil while the softer filament would behave as the more compliant
body of the tube allowing kink-resistant bending and twisting. The
difference in the durometer of the two materials does not need to
be substantial.
[0032] In another aspect of the invention as illustrated in FIG.
10, a mandrel 100 is used as part of an extrusion process. In
particular, the mandrel 100 is coated with a first layer 102 that
would be the resultant internal surface of the tube. A spring
reinforcement 104 would then be placed over the first layer 102,
and then an outer layer 106 would be extruded over the spring
reinforcement 104. An advantage of this embodiment is the resultant
tube is not being contoured based on the process itself. As a
result, a contoured section could be easily added to an end of the
tube providing improved movement of the tube. The addition of the
contoured section could be done by either insert-molding,
over-molding or melding (fusing) of the contoured section to the
tube. It is appreciated that the spring reinforcement 104 could be
a pre-wound wire placed around the first layer 102 or a wire
wrapped around the first layer 102. It is further appreciated that
the gaps between the wires are filled and that the final tube has
little or no voids or air bubbles.
[0033] In another embodiment of the invention as illustrated in
FIG. 8, another coating or outside layer 80 could be placed over
the spring reinforcement by means of a dipping process. In
particular, after the mandrel has been coated and the spring
reinforcement has been placed or wrapped, the assembly is then
dipped in a solvent based solution to form the outer layer 80 onto
the tube or sheath. It is appreciated that the final coating could
be formed on the resultant tube or sheath using a dipping process
either in place of or in addition to the outer layer formed by
extrusion. In other words, the final coating could be extruded
and/or dipped. It is preferable that the final coating is
impervious. An advantage of this embodiment is it allows a layer of
a desired material to be formed on the surface of the resultant
tube. In yet another embodiment of the invention, a thin flat sheet
of polyurethane having a specific width and thickness may be
wrapped around the mandrel as a coating. An advantage of this
embodiment is it forms an even and smooth coating and it gives some
control over the thickness of the coating.
[0034] As discussed above, the wire reinforcement could be
pre-wound or wound during each of the above processes. Moreover,
the material of the wire, the hardness of the wire, the pitch of
the windings and the shape of the wire could vary depending on the
surgical application of the tube or sheath. For example, the wire
may comprise a metallic and/or plastic material. The cross-section
of the wire may be round, flat, hexagonal or any other shape that
facilitates interlocking of the windings. The use of harder or
softer durometer materials is also important as to the inner or
outer layer of the tube. Another configuration of the invention
uses double reversed springs.
[0035] In another aspect of the invention, a braid such as a
polyester braid may be used instead of or in addition to the coil
spring to form a kink-resistant sheath as generally illustrated in
FIGS. 11-15. The braid may comprise of woven fibers made of
plastic, metal or any combination of plastics and metals. In one
configuration, a spring of length x is placed over a braid having a
length of approximately 2x, the excess braid is then inverted over
the spring to form a sheath having two layers of braid surrounding
the spring. It is appreciated that the braid may be heat fused to
prevent axial stretching. Furthermore, the braid may be insert
molded, fused or bonded onto the sheath.
[0036] FIG. 11 illustrates an exemplary braid 110 having a proximal
portion 112 and a distal portion 114 with a tube 116 having a
distal portion 118 and a proximal portion 120 attached to a handle
122. FIG. 12 illustrates the fusing of the proximal portion 112 of
braid 110 with the distal portion 118 of tube 116. FIG. 12 further
illustrates that the distal portion 114 of braid 110 may be insert
or over-molded in a partially deployed condition, fully deployed
condition or in a straight condition. FIG. 13 illustrates a braid
130 and a tube 132 extruded with a plastic material 134 prior to
fusing. FIG. 14 illustrates the fusing of the braid 130 and tube
132. Finally, FIG. 15 illustrates the coating of the braid 130 and
tube 132 with a solvent based solution either by dipping or
extrusion.
[0037] Although exemplary embodiments of the invention have been
shown and described, many other changes, modifications and
substitutions will now be apparent to those of ordinary skill in
the art, without necessarily departing from the spirit and scope of
this invention as set forth in the following claims.
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